Questions from a newbie

[Jem Berkes <jb...@pc9.org>]

I'm just getting into module development for the first time (thanks to 
impetus provided by Google's Summer of Code)... I've got a test 
environment with 2.1.6-alpha and have succeeded in writing minimal modules 
and getting them working on a live server. But I have a few nagging 
questions that I hope someone can help me with.

1) ap_hook_* functions... obviously, there are lots of these that are used 
to register hooks. Where can I find a reference list of the available 
functions? I'm looking through code of modules, and it leaves me 
wondering, how would I know what hook possibilities exist?

2) I'm having trouble navigating and finding facilities I need. Let's say 
I was looking for something that turns out to be satisfied by ap_fwrite(), 
in the API for filters. Where should I start, to lead myself to finding 
that function? I thought apr.apache.org but Google shows no mention of 
ap_fwrite within that site.

3) I can understand how a module can tie into Apache's normal processing 
to intercept connections, requests, etc. But what is the structure and 
mechanism by which one module can make use of another module? I can use C 
functions but there must be some kind of standardized interface for 
inter-modular calls?

For example, for SMTP support we are contemplating the protocol unit 
(mod_smtpd) passing on mail to a module that specifically delivers mail. 
How do those two entities communicate with each other? A mod_smtp_deliver 
would get a potentially large chunk of data (const char* ?) from mod_smtpd 
and deliver the mail via procmail, etc. This is a loose binding by the way 
since all received mails do not necessarily have to be delivered.

Re: Questions from a newbie

[Jem Berkes <jb...@users.pc9.org>]

> ... The other solution (letting mod_smtpd read the whole
> thing into a buffer and then passing the buffer) seems way too memory
> hungry for me.

I was trying to figure that out too. It seems like a bad idea to read the 
whole thing into memory because the buffer could easily require several 
tens of megabytes.

Re: Questions from a newbie

[Rian Hunter <ri...@MIT.EDU>]

Jem Berkes wrote:
> For example, for SMTP support we are contemplating the protocol unit 
> (mod_smtpd) passing on mail to a module that specifically delivers mail. 
> How do those two entities communicate with each other? A 
> mod_smtp_deliver would get a potentially large chunk of data (const 
> char* ?) from mod_smtpd and deliver the mail via procmail, etc. This is 
> a loose binding by the way since all received mails do not necessarily 
> have to be delivered.

I was thinking of calling the handlers, and letting the handlers read 
from the input_filters list in the request_rec, check out the 
ap_rgetline function. Does this sound like a bad idea to you? any 
security issues? The other solution (letting mod_smtpd read the whole 
thing into a buffer and then passing the buffer) seems way too memory 
hungry for me.
-rian